Oscar de Marcos is a Spanish football player who currently features for the Spanish football club Athletic Bilbao. He is a versatile player who can play as a midfielder, full-back and a forward.

De Marcos developed at the youth academy of Alaves and made his debut for the B team in 2007. In 2008 he was promoted to the first team and made 20 league appearances until 2009 when Bilbao snapped him up.

Since then De Marcos has gone from strength to strength and is now rated as one of the best young players in entire Europe. He was instrumental in Bilbao reaching the finals of the Europa League and the Copa del Rey.

De Marcos has played for Spain at the Under-20, Under-21 and Under-23 levels, but has yet to make his debut for the senior team.